1. Technical Field
The present invention relates to an ink container and a method of storing the ink, and more particularly, to an ink container and a method of storing the ink, capable of storing ink composition with excellent stability.
2. Related Art
An ink-jet recording method is a method of printing by ejecting small droplets of ink composition onto and attaching the small droplets to a recording medium. The ink-jet recording method is characterized in that an image having a high resolution and being of high quality can be printed at a high speed. An ink composition for use in the ink-jet recording method includes an aqueous solvent as a main component, a coloring component and a wetting agent such as glycerin for preventing clogging.
When a printing process is performed on a recording medium such as paper or a clothing material into which an aqueous ink composition has difficulty permeating or a recording medium such as a substrate or a film manufactured from metal, plastic and the like into which the aqueous ink composition can not permeate such as resins i.e., phenol, melamine, vinyl chloride, acryl and polycarbonate. The ink composition is required to have a component capable of stably attaching a coloring material to the recording medium.
In response to the above-mentioned requirement, a light-curable ink-jet ink including a coloring material, a light-curing agent (a radically polymerigable compound), a (photo-radical) polymerization initiator and the like has been disclosed (see U.S. Pat. No. 5,623,001). By using the ink composition in U.S. Pat. No. 5,623,301, it is possible to prevent spreading of the ink to the recording medium and improve image quality.
When an ink composition is to be cured by photo-radical polymerization, there is a possibility that a polymerization reaction (dark polymerization) may be caused by a thermal radical or the like and viscosity thereof could be thereby increased during storage. In order to solve the above-mentioned problems, JP-A-2004-196936 discloses a technology in which the concentration of dissolved oxygen is controlled to be within a predetermined range, and dark polymerization is prevented by inhibiting polymerization with oxygen.
However, in the technology disclosed in JP-A-2004-196936, the concentration of the dissolved oxygen is specified only at a specific temperature, and there were cases where a satisfactory effect was not obtained when ink was stored for a long period of time during which environmental temperature greatly varied.